Photo 3. As long as curves are kept gentle, breaking along the
scores only takes a couple of bends back and forth. Unscored sheet
styrene will flex A LOT before it actually breaks.

Photo 4. The front fuselage halves and "turtle deck"
fairing are kept in one piece until after they have been sanded
to the center seam of those halves (the level of the surface of
the surrounding scrap); it's just better that way...